Just a note about a problem I have seen discussed here many times. I also found a couple TSB's.

Ignition crossfire is real. Not that I doubted anyone...but I figured with good spark plug wires routed halfway decent it should not be a problem. WRONG!!

My '93 5.0L Ford Bronco had a missing/bucking/jerking/loss of power condition around 40-65 MPH going up hills on OD. After the truck downshifted into Drive (third) the problem would cease. I have had the vehicle for about a year. The PO had it "tuned up" (plugs, premium Belden wires, cap, rotor) about 30K miles ago.

Of course the original plug wire looms were broken on the passenger side. The wires had been bundled with plastic ties. The wires were routed "correctly" on the drivers side (within logical reason).

I thought about the 4/2 and 7/8 cylinder misfire so this morning I decided to try something.

I re-routed the wires so than the #4 and #8 wires were as far away from the others as possible. I did not place them in the factory plug wire holders. Instead I ran the #4 straight back under the upper intake plenum away from the others and secured it seperately with a wire tie. For the #8 I did the same. The #8 wire was long enough so I actually ran it down beside the upper intake, behind the valve cover and to the #8 spark plug.

I know the way I routed the wires was excessive and looks like poop. But guess what? The 254K mile 302 runs better than it has since I have owned it with not a hint of misfire. It actually has throttle response in OD now. Previously it would bog down as throttle was opened until it downshifted into 3rd. It will pull hills and not downshift nearly as much now. Slightly rough idle was really cleaned up, also.

I just thought that if anyone was experiencing this problem maybe this could help. It's totally free, easy, and reversible if it does not help.

Tomorrow I will replace the plugs and cap and rotor as well. I'm sure this condition does nothing good for them or the engine itself.

 

This is very interesting! I've had similar lugging problems in OD as well. It hasn't been as much a problem since I swapped out the 302 for a slightly modified 351, but it still happens some. I have known that my 35" tires with stock gearing cause most of the problem, but reading this has gotten me thinking. I'm going to try this out this weekend and see what happens. I'm glad you wrote this up.
Thanks!